电感耦合等离子体原子发射光谱(ICP-AES)法测定铸造铝ADC12中硅

在微波消解仪中以氢氧化钠溶解试样,然后滴加过氧化氢,使得铸造铝ADC12中的硅完全溶解,并采用电感耦合等离子体原子发射光谱(ICP-AES)法测定,硅的质量百分数平均值为10.31%的情况下,标准偏差0.09%,相对标准偏差(RSD)为0.83%。对比了国家标准方法中加热板消解法与微波消解法对硅加标回收率的影响,加热板消解法的加标回收率低于微波消解法,微波消解法辅助前处理样品,促使样品在短时间内反应完全,实验步骤简便,结果满意。     

微波消解-火焰原子吸收光谱法测定硅石中微量铁锰钙镁

本文提出硅石消解新技术--微波消解法.于聚氯乙烯消解罐中加硝酸、氢氟酸、高氯酸,程序加压升温分解硅石.微波消解法与冰浴法、加热消解法相比,可避免待测元素在分解过程带来的损失,且分解完全,酸用量少,操作简单、可靠.硅石经微波消解后采用火焰原子吸收光谱法检测铁、锰、镁、钙,铁、锰、镁、钙的回收率分别为97.3%～99.0%、104.4%～106.5%、95.7%～98.0%、103.1%～106.6%,与国家标准方法分析结果比较,相对误差均小于5%.     

测定土壤中微量铬的微波消解二苯卡巴肼分光光度法

研究了一种在密闭器内进行微波湿法消解进而用二苯卡巴肼分光光度法测定土壤中微量铬的方法,对微波消解的程序和溶剂等进行了试验和优化。与传统消解法相比,该法具有操作简便、省时,不沾污样品和不污染环境等优点,样品分析结果的相对标准偏差约为０．５％（ｎ＝８）,加标回收率为９７．５％－９９．０％,与国家标准方法测得的结果吻合。     

微波消解-冷原子吸收法定量测定人参中汞的研究

应用微波消解仪和原子吸收光谱仪 ,采用氢化物 冷原子吸收光谱法对人参中的汞的定量测定方法进行了研究。对微波消解仪的消解条件、氢化物 冷原子吸收方法的测定条件进行了探讨。在本法选择的条件下 ,回收率为 90 98%～ 1 0 8 96 % ,相对标准偏差为 8 0 4 %～ 1 5 77%。与国家标准方法的对比实验证明 ,两者无显著差异。     

落叶松与白桦树中微量及稀土元素的ICP-MS检测方法研究

利用微波消解法处理植物灰分样品,讨论了混合酸组成、混酸配比、固液比和微波消解时间对样品制备结果的影响.优选微波消解方案:微波压力(MPa)0.5、1.0、1.5、2.0,消解时间(min)4、3、3、10的微波程序,混合酸体系HNO3-HCl-HF-HClO4(体积比为6 ∶ 2 ∶ 1 ∶ 1).在此条件下, 进行了方法准确度实验和测量结果重复性实验, 该方法经植物国家标准物质(GBW07603)验证,微量元素测试结果的相对误差为1.06% ～5.60%,相对标准偏差为0.87% ～5.25%;稀土元素测试结果的相对误差为1.82% ～10.2%,相对标准偏差为2.14% ～8.00%.应用电感耦合等离子体质谱法(ICP-MS)同时测定植物灰分中21种微量元素和15种稀土元素.结果表明, 微波消解法处理植物灰分样品, 具有快速、简便、节省试剂、消解完全等特点, 测定结果的准确度和精密度令人满意.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定ADC12中硅

在微波消解仪中以氢氧化钠溶解试样,然后滴加过氧化氢,使得铸造铝ADC12中的硅完全溶解,并采用电感耦合等离子体原子发射光谱(ICP-AES)法测定,硅的质量百分数平均值为10.31％的情况下,标准偏差0.09％,相对标准偏差(RSD)为0.83％.对比了国家标准方法中加热板消解法与微波消解法对硅加标回收率的影响,加热板消解法的加标回收率低于微波消解法,微波消解法辅助前处理样品,促使样品在短时间内反应完全,实验步骤简便,结果满意.     

催化剂中钨的测定溶样方法的改进

研究了新的溶样方法——微波消解法,并将其与常规光度法相结合测定催化剂中钨。考察了测定条件,研究了消解用酸的种类、用量和不同的消解程序对消解效果的影响,确定了微波消解催化剂的最佳消解程序。将经微波消解处理的催化剂样品用常规光度法测定钨的含量,其相对误差小于2．0%,相对标准偏差小于1．3%。将微波消解法与常压敞口消解法进行对比,测定结果基本一致。微波消解法酸用量减少了约5．0倍,消解速度提高了3．5～6．7倍。该方法具有省时、省酸、样品损失少、无环境污染、测定结果准确可靠等优点。     

样品处理方法对测定汞的影响

研究了两种样品前处理方法——湿法消解法和微波消解法对汞测定结果的影响。结果表明，用微波消解法测得的结果要比传统的湿法消解法结果较为可靠，特别是对于难分解的样品(如化妆品)，尤其在含量很低时，要尽量使用微波消解。     

微波消解-火焰原子吸收光谱法测定污泥中铅

研究了微波消解-火焰原子吸收光谱法测定污泥中铅。应用正交试验设计法确定了微波消解试样的最佳条件。该法与传统敞口消解法测定结果吻合。样品测定结果的相对标准偏差（n=6）为1.5％～4．7％，加标回收率为93．0%-106．2％。该方法省时省酸，减少环境污染，改善了工作环境。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定铂金材料中杂质元素

建立了微波消解-电感耦合等离子体原子发射光谱（ICP-AES）法同时测定铂饰品国家标准物质中金、铜、铱、钴、钯、铑、钌7种杂质元素含量的方法。方法中7种元素的检出限为：钯与钌〈0.0001%,其它元素〈0.000 62%。经与国家标准物质认定值比对,结果满意。稀释系数95.5%-104.7%。方法测定结果与标准样品认定值一致,可满足铂金材料中杂质元素检测。     

Discrimination of Chinese traditional soy sauces based on their physico-chemical properties

This work aimed to classify the categories (produced by different processes) and brands (obtained from different geographical origins) of Chinese soy sauces. Nine variables of physico-chemical properties (density, pH, dry matter, ashes, electric conductivity, amino nitrogen, salt, viscosity and total acidity) of 53 soy sauce samples were measured. The measured data was submitted to such pattern recognition as cluster analysis (CA), principal component analysis (PCA), discrimination partial least squares (DPLS), linear discrimination analysis (LDA) and K-nearest neighbor (KNN) to evaluate the data patterns and the possibility of differentiating Chinese soy sauces between different categories and brands. Two clusters corresponding to the two categories were obtained, and each cluster was divided into three subsets corresponding to three brands by the CA method. The variables for LDA and KNN were selected by the Fisher F-ratio approach. The prediction ability of all classifiers was evaluated by cross-validation. For the three supervised discrimination analyses, LDA and KNN gave 100% predications according to the sample category and brand.     

液液萃取-场放大进样-毛细管电泳非接触式电导分离检测酱油中的安赛蜜

采用场放大进样（FASI）-毛细管电泳非接触式电导检测法（CE-C⁴D）,结合液液萃取（LLE）的样品净化预处理技术,分离检测了酱油中人工合成甜味剂安赛蜜。酱油样品经酸化后,用乙酸乙酯作为萃取剂,成功地消除了酱油中含有的大量无机盐等复杂基体对微量安赛蜜的干扰。实验对影响LLE萃取效率和FASI-CE-C⁴D分离检测的关键因素进行了讨论,特别是对样品净化前处理过程中萃取剂及用量、样品酸化pH值、萃取时间、萃取温度等条件进行了优化。结果表明,酱油中的安赛蜜可获得良好分离和灵敏检测,检出限和定量限分别为0.15 mg/kg和0.48 mg/kg。对市售酱油样品进行安赛蜜的加标回收测定,得到加标回收率为92.3%~108.1%,相对标准偏差＜8.0%。该法具有简单快速、灵敏高效、分析成本低的优点,能满足酱油中安赛蜜的分析检测要求。     

Method performance study of the determination of total nitrogen in soy sauce by the Kjeldahl method.

The objective of this collaborative study was to evaluate the proposed method for determining the total nitrogen in soy sauce by the Kjeldahl method submitted to the Codex Alimentarius Commission for endorsement in accordance with the protocol for the design, conduct, and interpretation of method-performance studies. The digestive conditions of the proposed method are the addition of 10 mL of H2SO4, 10 g (8 g by using a block digester) of K2SO4, and 1 mL of 20% CuSO4 x 5H2O and 80 min boiling period after the liquid is cleared by a heating device. Seventeen laboratories participated, analyzing five soy sauce samples as blind duplicates. Since the volume sampling method used in the JAS (Japanese Agricultural Standard) method showed lower accuracy of data because of the density of soy sauce, the method of sampling by weight was adopted as the proposed method. The total amount of outlier data was within acceptable limits for method-performance studies (< or = 22.2%). Lysine and ammonium sulfate recoveries for all laboratories were > or = 98% and > or = 99% respectively. The RSDr (repeatability relative standard deviation) values ranged from 0.4 to 1.3%, and the RSDR (reproducibility relative standard deviation) values were from 0.8 to 1.9%. HORRAT (RSDR/predicted RSDR) for the reproducibility showed 0.2 to 0.4, indicating acceptable precision of the method and excellent analytical performance.     

酱油中3-氯-1，2-丙二醇检测实验室间比对分析

介绍了由中国计量科学研究院化学所负责实施的酱油中3-氯-1,2-丙二醇检测实验室间比对情况,并针对该项目的检测方法、标准物质选择、前处理方法等进行了技术分析。21家参加比对实验室对样品l检测结果满意率85．7％,样品2结果满意率100％。建议实验人员在检测中可通过空白加标或应用质控样品等手段提高检测结果的准确度。     

气相色谱-三重四极杆串联质谱法同时测定调味品中的氨基甲酸乙酯和氯丙醇

建立了气相色谱-三重四极杆串联质谱(GC-MS/MS)同时测定调味品中氨基甲酸乙酯(EC)和氯丙醇(3-氯-1,2-丙二醇(3-MCPD)和2-氯-1,3-丙二醇(2-MCPD))的方法。样品添加同位素内标后,采用Extrelut^TM NT有机硅藻土填料进行基质固相分散萃取,先用正己烷淋洗除杂,再用乙酸乙酯-乙醚(20:80, v/v)混合溶剂洗脱被测物,洗脱液经浓缩后采用GC-MS/MS多反应监测(MRM)模式测定。EC、3-MCPD和2-MCPD的方法检出限依次为2、5和5 μg/kg,线性范围依次为5~1000 μg/kg(r=0.9997)、10~1000 μg/kg(r=0.9991)和10~1000 μg/kg(r=0.9995)。酱油、料酒(黄酒)、沙拉酱和方便面调味料4种基体中在20、100和400 μg/kg 3个水平加标测定的平均回收率和相对标准偏差(RSD,n=7)范围分别为EC: 87.7%~104%(RSD为4.3%~10.7%)、3-MCPD: 90.1%~109%(RSD为2.6%~10.2%)、2-MCPD: 90.9%~103%(RSD为3.0%~9.5%)。在部分酱油、料酒和方便面调味料中同时检测到了EC、3-MCPD和2-MCPD,在部分沙拉酱中检测到了EC或3-MCPD。该法准确、快速,适用于调味品中EC、3-MCPD和2-MCPD的同时检测。     

Rapid high-performance liquid chromatography method for the analysis of sodium benzoate and potassium sorbate in foods

A rapid and reliable method is presented for the determination of the preservatives sodium benzoate and potassium sorbate in fruit juices, sodas, soy sauce, ketchup, peanut butter, cream cheese, and other foods. The procedure utilizes high-performance liquid chromatography (HPLC) followed by UV diode array detection for identification and quantitation of the two preservatives. Liquid samples were prepared by diluting 1 ml of the sample with 10 ml of an acetonitrile/ammonium acetate buffer solution. Samples of viscous or solid foods were prepared by blending the sample with the same buffer solution in a 1:5 ratio followed by a dilution identical to liquid samples. All samples were filtered to remove particulate matter prior to analysis. The HPLC determination of the preservatives was performed using a reversed-phase C18 column and UV detection at 225 nm for sodium benzoate and 255 nm potassium sorbate. The percentage of preservative in the sample was calculated by external standard using authentic sodium benzoate and potassium sorbate. Apple juice, apple sauce, soy sauce, and peanut butter, spiked at 0.10 and 0.050% for both sodium benzoate and potassium sorbate, yielded recoveries ranging from 82 to 96%. The method can detect 0.0010% (10 mg/l) of either preservative in a juice matrix.     

Simultaneous analysis of 2‐methylimidazole, 4‐methylimidazole,and 5‐hydroxymethylfurfural potentially formed in fermented soy sauce by “quick,easy, cheap,effective, rugged,and safe” purification and UHPLC with tandem mass spectrometry

2‐Methylimidazole, 4‐methylimidazole and 5‐hydroxymethylfurfural are harmful by‐products potentially formed via Maillard reaction in fermented soy sauce. The present study proposed a new method based on “quick, easy, cheap, effective, rugged, and safe” purification and ultra high performance liquid chromatography with tandem mass spectrometry for the simultaneous analysis of 2‐methylimidazole, 4‐methylimidazole and 5‐hydroxymethylfurfural in fermented soy sauce. The sample was dissolved in water after addition of internal standard 4‐methylimidazole‐d₆ and extracted with acetonitrile. After dehydration, it was centrifuged and the supernatant was subsequently purified using two sorbents namely primary‐secondary amine and multi‐walled carbon nanotube. Three target analytes were separated by gradient elution and determined under multiple reactions monitoring mode. The limit of detection, matrix effect, recovery and precision of the developed method were investigated. Results found that three target analytes displayed excellent linearity in concentration range of 1–250 μg/L. Limit of detection was in the range of 0.3–1 μg/kg for three target analytes. The mean recoveries for fermented soy sauce samples at three spiked concentrations were in the range of 91.2–112.5%, and the intra‐ and interday precision were in the ranges of 3.6–9.2 and 7.1–10.8%, respectively. This validated method was successfully applied to determine 2‐methylimidazole, 4‐methylimidazole and 5‐hydroxymethylfurfural concentrations in fermented soy sauce.     

分散固相萃取结合气相色谱-高分辨质谱快速筛查酱油中多种氯丙醇

建立了酱油中1，3-二氯-2-丙醇、2，3-二氯-1-丙醇、3-氯-1，2-丙二醇和2-氯-1，3-丙二醇的分散固相萃取-气相色谱-高分辨质谱快速筛查检测方法。样品采用乙酸乙酯提取，提取液浓缩后经N-丙基乙二胺净化，气相色谱-高分辨质谱测定，内标法定量。结果表明，该方法对于酱油中4种氯丙醇的定量限为0.5~10 μg/kg。在3个浓度水平下的加标回收率为78%~103%；相对标准偏差均不大于8.8%。该方法快速、简便、准确、灵敏，可作为酱油中4种氯丙醇的有效检测方法。     

顶空固相微萃取-气相色谱-质谱法快速测定酱油中的挥发性风味成分

建立了一种快速简便地测定酱油中挥发性风味成分的顶空固相微萃取（HS-SPME）-气相色谱-质谱法(GC-MS)。以2-辛醇为内标,考察了萃取头、萃取时间、离子强度、萃取温度对酱油样品中挥发性风味物质萃取的影响。该方法对酱油中常见挥发性风味成分的测定有良好的重复性和回收率,对常见挥发性物质的定量比较准确。优化的HS-SPME条件为：涂层厚度为85 μm聚丙烯酸酯(PA)萃取纤维头,于45 ℃、NaCl质量浓度为250 g/L下对酱油样品顶空吸附40 min,于250 ℃下解吸2 min后进行GC-MS分离鉴定。酱油样品的分析结果表明,其挥发性风味物质中含量较高的是醇、酸、酯和酚类,此外还有一些羰基化合物和杂环化合物。     

Sensitive method for the determination of 1,3-dichloropropan-2-ol and 3-chloropropane-1,2-diol in soy sauce by capillary gas chromatography with mass spectrometric detection

This paper reports the development of a highly selective and sensitive method for the determination of parts-per-billion level of 1,3-dichloropropan-2-ol (1,3-DCP) and 3-chloropropane-1,2-diol (3-MCPD) in soy sauce using capillary gas chromatography with mass spectrometric detection. Samples were homogenised, mixed with sodium chloride solution and then adsorbed on silica gel. The loaded silica gel was packed into a chromatographic column, from which chloropropanols were extracted by elution with ethyl acetate. Heptafluorobutyric acid anhydride was added to the concentrated eluant to derivatise the chloropropanols and the derivatised analytes were separated by gas chromatography, identified and quantified by mass spectrometry. A linear relationship between the concentration of the two chloropropanols and the detector response was obtained over the concentration range of 10-1000 microg/kg. Precision of the method was satisfactory at about 5%, and recoveries of 1,3-DCP and 3-MCPD from soy sauce samples spiked at 25 microg/kg were 77 and 98%, respectively. The limit of quantitation of the method was found to be about 5 microg/kg for 1,3-DCP and 3-MCPD, respectively meeting the requirements of tolerance limits adopted by different international institutions and governments around the world. This paper is the first of its kind in reporting an analytical procedure for the simultaneous separation and determination of 3-MCPD and 1,3-DCP, a more potent contaminant, at low microg/kg level.